DE1763885A1 - Circuit arrangement for limiting the current in a series control circuit - Google Patents
Circuit arrangement for limiting the current in a series control circuitInfo
- Publication number
- DE1763885A1 DE1763885A1 DE19681763885 DE1763885A DE1763885A1 DE 1763885 A1 DE1763885 A1 DE 1763885A1 DE 19681763885 DE19681763885 DE 19681763885 DE 1763885 A DE1763885 A DE 1763885A DE 1763885 A1 DE1763885 A1 DE 1763885A1
- Authority
- DE
- Germany
- Prior art keywords
- current
- transistor
- voltage
- base
- circuit arrangement
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Classifications
-
- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05F—SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES
- G05F1/00—Automatic systems in which deviations of an electric quantity from one or more predetermined values are detected at the output of the system and fed back to a device within the system to restore the detected quantity to its predetermined value or values, i.e. retroactive systems
- G05F1/10—Regulating voltage or current
- G05F1/46—Regulating voltage or current wherein the variable actually regulated by the final control device is dc
- G05F1/56—Regulating voltage or current wherein the variable actually regulated by the final control device is dc using semiconductor devices in series with the load as final control devices
- G05F1/565—Regulating voltage or current wherein the variable actually regulated by the final control device is dc using semiconductor devices in series with the load as final control devices sensing a condition of the system or its load in addition to means responsive to deviations in the output of the system, e.g. current, voltage, power factor
- G05F1/569—Regulating voltage or current wherein the variable actually regulated by the final control device is dc using semiconductor devices in series with the load as final control devices sensing a condition of the system or its load in addition to means responsive to deviations in the output of the system, e.g. current, voltage, power factor for protection
- G05F1/573—Regulating voltage or current wherein the variable actually regulated by the final control device is dc using semiconductor devices in series with the load as final control devices sensing a condition of the system or its load in addition to means responsive to deviations in the output of the system, e.g. current, voltage, power factor for protection with overcurrent detector
- G05F1/5735—Regulating voltage or current wherein the variable actually regulated by the final control device is dc using semiconductor devices in series with the load as final control devices sensing a condition of the system or its load in addition to means responsive to deviations in the output of the system, e.g. current, voltage, power factor for protection with overcurrent detector with foldback current limiting
Landscapes
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- General Physics & Mathematics (AREA)
- Radar, Positioning & Navigation (AREA)
- Automation & Control Theory (AREA)
- Continuous-Control Power Sources That Use Transistors (AREA)
- Control Of Electrical Variables (AREA)
Description
Schaltungsanordnung zur Strombegrenzung einer Serienregelschaltung Die Erfindung bezieht sich auf eine Schaltungsanordnung zur Stromregelung eines Serienspannungsreglers, der aus Gleichstromregelstrecke,Verstärker, Diskriminator und Vergleichsspannung besteht, wobei die Regelung des Stromes von der Grösse des Lastwiderstandes abhängig ist.Circuit arrangement for limiting the current in a series control circuit The invention relates to a circuit arrangement for regulating the current of a Series voltage regulator consisting of a direct current control system, amplifier, discriminator and comparison voltage exists, the regulation of the current being dependent on the magnitude of the Load resistance is dependent.
Zur Regelung des Stromes, insbesondere bei Überlast und Kurzschluss, ist es bekannt, dass man entweder thermische, magnetische oder elektronische Sicherungen verwendet.To regulate the current, especially in the event of overload and short circuit, it is known to have either thermal, magnetic, or electronic fuses used.
Bei Schaltungen, die mit Halbleitern aufgebaut sind, verwendet man aus Gründen der Regelgeschwindigkeit hauptsächlich sogenannte elektronische Sicherungen. Einfache elektronische Sicherungen verwenden als Stromkriterium den Spannungsabfall an einem ohmschen Widerstand, aufwendige elektronische Sicherungen benutzen die magnetische Wirkung des Stromes.For circuits that are constructed with semiconductors, one uses for reasons of the control speed mainly so-called electronic fuses. Simple electronic fuses use the voltage drop as a current criterion on an ohmic resistor, elaborate electronic fuses use the magnetic effect of the current.
Eei einfachen elektronischen Sicherungen muss meist der Spannungsabfall in der Höhe der Ansprechschwelle eines Halbleiters liegen, also üblicherweise den Spannungswert der Basis-Emitter-Spannung eines Transistors. Soll dieser Spannungsabfall, der als reine Verlustspannung aufgefasst werden muss, wesentlich kleiner sein, müssen zusätzliche Kompensationsmassnahmen gegen den Temperatureinfluss auf die Lasis-Emitter-Spannung des die Stromregelung bewirkenden Transistors ergriffen werden.With simple electronic fuses, the voltage drop usually has to occur are at the level of the response threshold of a semiconductor, so usually the Voltage value of the base-emitter voltage of a transistor. Should this voltage drop, which must be understood as a pure loss voltage, must be much smaller additional compensation measures against the influence of temperature on the Lasis emitter voltage of the transistor causing the current regulation are taken.
Der Erfindung lag die Aufgabe zugrunde, den nötigen Spannungsverlust bei einfachen elektronischen Sicherungen möglichst gering zu halten und trotzdem ohne besonderen Schaltungsaufwand eine thermisch stabile Schaltungsanordnung zu erreichen.The invention was based on the object of the necessary voltage loss to keep it as low as possible with simple electronic fuses and yet a thermally stable circuit arrangement without any special circuit complexity reach.
Eine sehr einfache Lösung der Aufgabe ergab sich durch die erfindungsgemässe Mitbenutzung der sowieso vorhandenen Basis-Emitter-Spannung des Leistungstransistors in der Gleichstromregelstrecke, wobei die Temperaturabhängigkeit eben dieser Basis-Emitter-Spannung zur Kompensation der Temperaturabhängigkeit der Basis-Emitter-Spannung des den Strom regelnden Transistors dient, wenn beide Transistoren thermisch gekoppelt sind.A very simple solution to the problem resulted from the invention Shared use of the base-emitter voltage of the power transistor, which is present anyway in the direct current controlled system, the temperature dependence of this base-emitter voltage to compensate for the temperature dependence of the base-emitter voltage of the current regulating transistor is used when both transistors are thermally coupled.
Diese Schaltungsanordnung hat einen sehr kleinen .Aufwand an Schaltelementen und benötigt eine sehr kleine Spannung zur Regelung des Stromes.This circuit arrangement has a very small cost of switching elements and requires a very small voltage to regulate the current.
Nachstehend folgt die Beschreibung anhand des Prinzipschaltbildes. Ein einer Stromquelle entnommener Strom fliesst von der Eingangsklemme 1 über den Transistor T,, den Widerstand R4, die Ausgangsklemme 2, durch den LastwUderstand RL und die Klemmen 3 und 4 zurück zur Stromquelle. Die Ausgangsspannung U, wird in bekannter Weise durch den Spannungsteiler R5, R6, den Transistor T4, Referenzelement Z2 und die Transistoren T1, T2, sowie den Widerstand. R,, stabil gehalten. Der Transistor T4 regelt den Basisstrom des Transistors T2, dieser wiederum den Basisstrom des Transistors T l. Die Regelung des durch den Widerstand R4 fliessenden Stromes erfolgt durch das Leitendwerden des Transistors T3, was durch die Spannung an R2 und R4 bewirkt wird. Am Widerstand R2 steht ein Teil der Basis-Emitter-Spannung des Transistors T1 zu dem sich der Spannungsabfall des den Widerstand R4 durchfliessenden Stromes addiert. Der Transistor T3 wirkt dann in bekannter Weise auf den Basisstrom des Transistors T2 und damit auf ,den fiasisstrom des Transistors T1 ein. Mit den Widerständen R2, R3 und R4 kann also eine Strombegrenzung in beliebiger Höhe eingestellt werden. The following is a description based on the basic circuit diagram. A current drawn from a current source flows from the input terminal 1 via the transistor T ,, the resistor R4, the output terminal 2, through the load resistor RL and the terminals 3 and 4 back to the current source. The output voltage U, is determined in a known manner by the voltage divider R5, R6, the transistor T4, reference element Z2 and the transistors T1, T2, and the resistor. R ,, kept stable. The transistor T4 regulates the base current of the transistor T2, which in turn controls the base current of the transistor T l. The current flowing through the resistor R4 is regulated by the transistor T3 becoming conductive, which is caused by the voltage across R2 and R4. A part of the base-emitter voltage of the transistor T1 to which the voltage drop of the current flowing through the resistor R4 is added is present at the resistor R2. The transistor T3 then acts in a known manner on the base current of the transistor T2 and thus on the fiasis current of the transistor T1. The resistors R2, R3 and R4 can be used to set any current limit .
Die Ausgangsspannung U, verringert sich dadurch in Abhängigkeit vom Lastwiderstand R L, wobei der Strom einen konstanten Wert behält. Da aber bei sinkender Ausgangsspannung Udie Spannung zwischen Kollektor und Emitter des Transistors T1 wächst und damit dessen Verlustleistung, empfiehlt sich in manchen Anwendungsfällen eine Erweiterung der Schaltungsanordnung.The output voltage U decreases as a function of the Load resistance R L, the current maintaining a constant value. But there with decreasing Output voltage U the voltage between the collector and emitter of transistor T1 grows and with it its power loss, is recommended in some applications an extension of the circuit arrangement.
Eine Z-Diode Z1 hat eine etwas niedrigere Spannung als die Ausgangsspannung U.. Der Widerstand R8 lässt einen Strom durch die Z-Diode Z2 fliessen. Zwischen der Basis des Transistors T3 und der Spannung der Z-Diode Zl-herrscht ein kleiner Spannungsunterschied, es fliesst also auch nur ein kleiner Strom durch die Widerstände R? und R2, denn der Transistor T3 ist noch gesperrt. Bei einsetzender Strombegrenzung sinkt die Ausggngespannung UA und damit wird die Potentialdifferenz am Widerstand R7 grösser. Folglich kann jetzt ein grösserer Strom in die Basis des nun leitenden Transistor T3 fliessen, wap einen zusätzlichen Strom durch den Transistor T3 hervorruft. Dieser Strom verringert aber den Basisstrom des Transistors T2 und dadurch den Basisstrom,des Transistors T1. Der Strom durch die Kollektor-Emitter-Strecke des Transistors T1 wird dadurch verringert. Man erhält bei richtiger Dimensionierung des Widerstandes R7 eine rückbiegende Strom-Spannungskennlinie. Durch Vergrössern des Lastwiderstandes RL erfolgt Übergang von der Stromregelung zurück in die Spannungsregelung. Wird der Widerstand R7 durch eine Diode ersetzt, deren Durchlassrichtung von der Z-Diode nach der Basis des Transistors T 3 gerichtet ist, erfolgt ein völliges Sperren der Transistoren T1 und T2, was nur durch Abtrennen von der Stromquelle und Beseitigung der Üterlast aufgehoben werden kann.A Zener diode Z1 has a slightly lower voltage than the output voltage U .. The resistor R8 allows a current to flow through the Zener diode Z2. There is a small voltage difference between the base of the transistor T3 and the voltage of the Zener diode Zl-so there is only a small current flowing through the resistors R? and R2, because the transistor T3 is still blocked. When the current is limited, the output voltage UA drops and the potential difference across the resistor R7 increases. As a result, a larger current can now flow into the base of the now conductive transistor T3, causing an additional current through the transistor T3. However, this current reduces the base current of the transistor T2 and thereby the base current of the transistor T1. The current through the collector-emitter path of the transistor T1 is reduced as a result. If the resistor R7 is dimensioned correctly, a current-voltage characteristic curve that bends back is obtained. By increasing the load resistance RL, there is a transition from current control back to voltage control. If the resistor R7 is replaced by a diode, the forward direction of which is directed from the Zener diode to the base of the transistor T 3, the transistors T1 and T2 are completely blocked, which can only be canceled by disconnecting the current source and removing the overload .
Claims (1)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE19681763885 DE1763885A1 (en) | 1968-08-30 | 1968-08-30 | Circuit arrangement for limiting the current in a series control circuit |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE19681763885 DE1763885A1 (en) | 1968-08-30 | 1968-08-30 | Circuit arrangement for limiting the current in a series control circuit |
Publications (1)
Publication Number | Publication Date |
---|---|
DE1763885A1 true DE1763885A1 (en) | 1972-01-13 |
Family
ID=5697782
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
DE19681763885 Pending DE1763885A1 (en) | 1968-08-30 | 1968-08-30 | Circuit arrangement for limiting the current in a series control circuit |
Country Status (1)
Country | Link |
---|---|
DE (1) | DE1763885A1 (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE2504648A1 (en) * | 1974-02-04 | 1975-08-07 | Matsushita Electric Ind Co Ltd | DEVICE TO PREVENT OVERCURRENT OR OVERVOLTAGE |
WO1989007853A1 (en) * | 1988-02-10 | 1989-08-24 | Reinhard Kalfhaus | Active filter |
-
1968
- 1968-08-30 DE DE19681763885 patent/DE1763885A1/en active Pending
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE2504648A1 (en) * | 1974-02-04 | 1975-08-07 | Matsushita Electric Ind Co Ltd | DEVICE TO PREVENT OVERCURRENT OR OVERVOLTAGE |
WO1989007853A1 (en) * | 1988-02-10 | 1989-08-24 | Reinhard Kalfhaus | Active filter |
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